I don't know if the engine will mate up the a/t trans bellhousing. Last US diesel was the 86 pickup truck, which used the KM145 5 spd, a similar 4spd m/t, or a torqueflite based 3spd a/t, not the Aisin Warner KM148 4spd a/t. The 2.6 4spd a/t like yours has a really loose torque converter (tc hereinafter), with a stall speed of about 2400, suited to the rpm vs. torque characteristics of a gas and spark motor like the 2.6 and 3.0 in a fairly heavy suv. Diesels like lower rpms than foogas motors, and make more torque at those lower rpms, and the converter stall speed may be too high. The we get to gearing. The truck is geared based on foogas motor rpm ranges. A lower revving diesel needs a lower numerically diff gear ratio. In your case, with a small diff, I think you have the stock 4.625, the 3.91 from the pickup, or a 3.55.

Given all that, plus all the wiring changes and fuel system changes, if you want a diesel, go buy a 'Zu Spacecab diesel pickup, and you'll come out cheaper.

In your shoes, the most bang for the buck is the turbo on a sound engine rebuild, or just the Starion FI without the turbo. I think the turbo with engine rebuild would cost about one third the bucks for a diesel swap. That's roughly $2000 vs. $6000...